Serum IL-6 and CRP in Childhood as Predictors of Psychosis and Depression in Young Adult Life

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Presentation First Author:

Golam Khandaker

Abstract:

Introduction: Cytokine mediated communication between the immune system and the brain has been implicated in the pathophysiology of psychosis and depression. Meta-analyses of cross-sectional studies suggest increased serum interleukin (IL) 6 and C-reactive protein (CRP) in first episode psychosis, acute psychotic relapse, and depression; however, longitudinal studies are scarce. We predicted that higher levels of IL-6 and CRP in childhood would be associated with future risks of psychosis and depression. Methods: We used data from approximately 4500 individuals from the general population ALSPAC birth cohort. Serum IL-6 and CRP were measured at age 9 years, and psychiatric assessments were undertaken at age 18 years. Results: After adjusting for gender, age, BMI, ethnicity, social class, past psychological problems, and maternal depression, participants in the top third of IL-6 values compared with the bottom third at age 9 were more likely to develop psychotic experiences (PE) at age 18 (adjusted odds ratio [OR] 1.81 (95% CI 1.01-3.28). The risks of psychotic disorder and of depression at age 18 were also increased with higher IL-6 at baseline; adjusted OR 2.40 (95% CI 0.87-6.62), and 1.55 (95% CI 1.13-2.14), respectively. The associations between IL-6 and risks of PE and depression were consistent with a dose-response relationship. Conclusions: Higher levels of IL-6 in childhood are associated with risks of psychotic outcomes and depression in young adulthood. Processes in the inflammatory pathway may be targets for therapeutic intervention and prevention for these disorders. Inflammation might explain the high comorbidity between schizophrenia, depression, cardiovascular disease, and diabetes.